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Cc: Jeffrey Scofield <jeffsco@psellos.com>, Caml List <caml-list@inria.fr>
From: Jeffrey Scofield <jeffsco@psellos.com>
Date: Sat, 11 Aug 2012 01:52:52 -0700
To: Benedikt Meurer <benedikt.meurer@googlemail.com>
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Subject: [Caml-list] ARM code generator problem

Benedikt,

> If you look at destroyed_at_oper in asmcomp/arm/proc.ml, you'll see that
> d7 (s14+s15) is marked as destroyed for those operations where it is
> used as scratch register.

I definitely see d7 being overwritten in the way I described, and I
don't think I've changed these parts of the code.  Most of the work
was in reformatting the output for the iOS assembler.  There are
some smallish changes to the linkage for calling functions like
sin() and cos().

I'll look to see how destroyed_at_oper is working, maybe it will
explain things.

I made a pretty small file (35 lines or so) that shows the problem.
Unfortunately, I don't have access to a Linux/ARM machine, so I can't
easily try it on an unmodified version of OCaml 4.00.0.  If I still
think there's a problem after figuring out destroyed_at_oper, I'll send
you a description in private mail.

> If possible, it would probably also make sense to merge some of the iOS
> related code into the upstream ARM backend, in case you are interested.

I'd definitely be interested, once I get things working reasonably well.

Thanks for the help.

Jeffrey